1. Field of the Invention
The present invention relates to an image forming apparatus that includes a cleaning device having a noise reduction mechanism, and an image forming apparatus that incorporates the cleaning device.
2. Discussion of the Background
A background image forming apparatus using electrophotography generally includes a photosensitive drum serving as an image carrier. The surface of the photosensitive drum is charged by an electrical discharge method. The charged surface of the photosensitive drum is then exposed to a laser beam generated in accordance with image data to form an electrostatic latent image on the charged surface of the photosensitive drum. The electrostatic latent image is then rendered into a visible image with toner. The visible toner image formed on the photosensitive drum is transferred onto a recording medium (e.g., paper) through a transfer process and the image is fixed on the recording medium, after which the recording medium bearing a fixed image thereupon is output.
Such image forming apparatuses generally employ a cleaning device to remove any toner remaining on the surface of the photosensitive drum so that subsequent image processing is not affected by the residual toner. In so doing, noise may be generated due to friction between the photosensitive drum and the cleaning device.
More specifically, the friction between the photosensitive drum and a cleaning blade of the cleaning device causes the blade to alternately stick and slip, or chatter. The chatter causes vibration that becomes a source of high-pitched noise. Further, the vibration is transmitted from the cleaning blade to the frame (hereinafter referred to as the cleaning frame) that holds the cleaning blade. As a result, the cleaning frame generates noises (also called chatter).
The residual toner is an obstacle for a subsequent image forming process and needs to be removed before starting the next process. Accordingly, since the cleaning device is indispensable to remove the residual toner from the surface of the photosensitive drum, reduction of such noise is a must.
A variety of configurations are proposed to reduce such noise. For example, Japanese Patent Laid-Open Application Publication No. H10-97158-A describes a weight fixed in the photosensitive drum. With the weight, it is possible to avoid resonance in the photosensitive drum; however, it is not possible to avoid vibration of the cleaning blade. Accordingly, noise is still generated at the cleaning blade.
Japanese Patent Laid-Open Application Publication No. 2005-338211-A describes the cleaning blade having a different resonance frequency from the resonance frequency of the image carrier. Further, No. 2005-215163 describes that the vibration frequency generated by the chatter between cleaning blade and the image carrier is set to be different from the resonance frequency of the cleaning blade. However, when the vibration is transmitted to the cleaning frame from the cleaning blade, the cleaning frame generates noise.
Further, Japanese Patent Laid-Open Application Publication No. 2000-132025 describes a weight fixed to the cleaning blade by a screw. However, it is not a way to prevent the vibration of the cleaning blade: Accordingly, when the vibration is transmitted to the cleaning frame, the cleaning frame generates noise.